For the decorating of glass articles with paint, such as bottles, jars and similar articles, it is necessary to take them to the loading station of a decorating machine where these articles are clamped and transferred to one or two decorating stations and finally, once these articles have been decorated, are transported to an lehr, so the paint, by means of heat, will adhere to the recently decorated articles.
One of the better known techniques for bottle or jar decoration is the screen process. In this process, the bottles or jars are transported by their ends to a decorating machine that includes a paint reservoir with a screen or stencil in the lower section. Each screen includes a decorating pattern in accordance to the design that one desires to print on the container.
By means of this process, once the bottle is set up in horizontal position in the first printing station of the decorating machine, it is rotated on supporting members located on the top and bottom ends of the bottle, it is moved towards a printing frame that has a decorating screen. The support members are arranged opposite one to the other leaving a space between them to receive the bottle. A squeegee or applicator on the upper part of the printing frame presses the decorating screen assuring that the paint is applied correctly on the profile or section desired on the bottle when this is rotated over the screen.
One of the main decorating machines of the previous art, is generally made up of a support structure, a driving shaft set horizontally between the supporting structure, the shaft having integrated a series of transporting stations which receive only a bottle to be decorated and pass this intermittently toward decorating stations. One decorating screen set horizontally over one of the transporting stations makes contact with the surface of the bottle during the decorating stage. Such screen has a sliding movement from front to back while the bottle rotates over its own axis, thus decorating by means of such movements the desired section of the bottle.
In case of decorating two bottles, the machine has two screens, set parallel with respect to the surface of the container, such screens being separated a certain distance one in front of the other. Because the decorating machine has at least six transporting stations, each station moves one single article to be decorated. Nevertheless, due to the fact that the transportation stations have a rotating movement on their own axis, in the sequence of movement of the stations, the first article is decorated by the front screen (second screen) while the second article makes contact with the back screen (first screen). Such movement allows two stations to decorate simultaneously two bottles with the same decorating pattern.
Notwithstanding the previous description, one of the main disadvantages of the type of decorating machines described above, is that the articles are only decorated with a single color. Thus, in case the bottle or article requires two or more colors, it is necessary to pass the recently decorated bottles again to the decorating machine to print the next or several decorating colors.
In order to avoid the disadvantages of the previous art, the U.S. Pat. No. 3,735,699 issued to Albert Koelschbach, describes a multicolor offset screen printing apparatus for producing a multi-color image on an object, by means of the known silk screen process, wherein there are a number of silk screens each with its own decorating pattern, the number of screens being equal to the number of colors to be employed. The decorative print is applied by a contact blade to an associated silk screen. An intermediate color carrier such as a belt or a plurality of rollers receives a colored image from each screen and applies the colored image in sequence to an article by rolling contact between the article and the intermediate belt or rollers.
Nevertheless, even if the Koelschbach machine has the capacity of decorating two or more colors in one sequence, one of the disadvantages of such machine is that the decorating of the articles is in individual form, that is, only one article per station, thus the process is slow, due mainly to the fact that today they are manufactured in greater quantities and it is required to decorate a greater quantity of glass or similar articles.
Other apparatuses for printing objects are described in the Patents No. DE 1571842; U.S. Pat. No. 3,783,777; and FR 2239344. For example, is Patent DE 1571842 is refers to a machine for decorating bottles or similar articles of the type that includes: a supporting structure; a rotatable shaft coupled in the supporting structure, to rotate over its own axis with an intermittent movement; a plurality of transporting stations connected to said shaft to rotate together with said drive shaft; supporting members for each transporting station, each supporting member being arranged to transport a cylindrical article as for example from a loading position to an unloading position of the machine; drive means connected to the rotatable shaft, said rotatable shaft and said transporting stations being rotated together by means of the drive means, and a printer screen for each two transporting stations, said screen being located towards and coinciding with a surface of the bottles to be decorated wherein the supporting members comprise means for supporting a cylindrical article for each of the transporting stations. Said supporting member is positioned for each one of the printing screens in order to simultaneously print at least two bottles--one for each of the transporting stations--with a color and a single printer screen.
However, patent No. DE 1571842 refers to a machine for decorating bottles, which is arranged to transport a cylindrical article for each station and uses a printer screen for each two transporting stations. The main problem of this machine is that each bottle is supported in an independent station, so that, a large printer screen is required to decorate simultaneously two bottles. With this arrangement, it is not possible decorate two articles or bottles simultaneously in a sole station. Neither is it possible to decorate at least two bottles, with three different to decorate screens or decorating at least two bottles with four different decorating screens.
U.S. Pat. No. 3,783,777 dated on Jan. 8, 1974, of Richard J. Killen, also claims an apparatus for imprinting objects such as bottles or the like. Said apparatus comprises a main conveyor including a drive shaft and, a series of article carriers connected to the conveyor for advancement thereby along a path toward a printing station. Flanking opposite straight sides of the conveyor are first and second assemblies, which are individually movable on guides along the opposite sides of the bottle conveyor. The assemblies support identical squeegee conveyors, respectively. Carried with the squeegee conveyors are identical tiltable stencil screens, respectively. Thus, the movable assemblies each include an inside tiltable stencil screen, an outside color container to provide a color pool, and a squeegee conveyor for carrying color from its pool to its stencil screen, each squeegee conveyor being adjustably mounted upon its carriage.
However one of the first disadvantages of this apparatus is that, for printing three or more colors on the containers, it is necessary to add more squeegee conveyors through the length of the apparatus.
Finally, the patent FR-A-2 239 344 discloses a dispositive or device for printing caps or similar articles. The first part of the specification is described to print caps are over its top part (see FIGS. 1-3). In this first embodiment, it is necessary to maintain the cap or caps fixed and retained in one of its extremities.
In a second embodiment of the French patent, the device is described for decorating bottles. However it is only possible to print a bottle for one printing station. In this case the bottles are feeding--one by one--by means of the transporting stations toward each one of the printing stations.
In view of the above, the present invention refers to a method and a machine for decorating bottles or similar articles of the type that includes: a supporting structure; a rotatable shaft coupled in the supporting structure, to rotate over its own axis with an intermittent movement; a plurality of transporting stations connected to said shaft to rotate together with said rotatable shaft, each transporting station having an individual supporting member, which are arranged in a position one in front of the other, leaving a space between each other to hold a container by its neck and bottom respectively, to transport the container from a loading position to an unloading position of the machine; drive means connected to the rotatable shaft, said rotatable shaft and said transporting stations being rotated together by means of the drive means; and, a printer screen for each one of the transporting stations, said printer screens being located toward and coinciding with a surface of the container to be decorated, the improvements characterized by comprising: at least two holding means for each one of the supporting members, for holding of the bottom of at least two containers; and, at least two holding means for each one of the supporting members, for holding the neck of at least said two containers, said holding means being arranged symmetrically in order that said two containers can be printed with a single printer screen for each printing station, each printer screen being adjusted parallel or angularly with respect to the surface of the containers in order to decorate simultaneously at least said two containers during each printing stage.